Jake Gyllenhaal's sister Maggie inspired his childhood dreams of acting.

The 38-year-old star has revealed how seeing the actress, now 41, on stage as a child pushed him to try it himself, and ''it felt really right''.

He told 'Entertainment Tonight': ''Ever since I saw my sister act... I saw her on stage and thought, 'That looks like a whole lot of fun.

''Then I tried my hand at it and it felt really natural. It felt really right and I enjoyed it so much...

''I think I was about six or seven years old. And then it's just been like that forever.''

The siblings both starred in 'Donnie Darko' in 2001, and he has since appeared in the likes of 'Brokeback Mountain', 'Zodiac', 'Love & Other Drugs' and 'Nightcrawler'.

Sister Maggie has also enjoyed a very successful career with performances on the big screen in films like 'The Dark Knight', 'Mona Lisa Smile', 'Hysteria' and 'Frank' as well as TV and stage roles.

Although Jake as inspired by her, the siblings have disagreed over certain aspects of their career when it comes to changing appearances for a role.

He underwent a grueling workout regime prior to playing the role of middleweight boxing champion Billy Hope in the 2015 movie 'Southpaw', but Maggie insisted he shouldn't change himself to suit his parts.

He previously said: ''My sister and I have the argument often. I've lost weight or learned a new skill and she's said: 'You don't have to change your body to play a character', and there are times where I agree and other times I don't.''

And he suggested it is an added ''craft'' if an actor can transform their body when they take on the role of different characters.

He added: ''I mean, putting the time into preparation, being agile, no, I don't think transforming your body physically had anything to do with the craft of acting.

''Although no matter how far you push yourself, to understand even the idea of that is to understand even the idea of that is almost close to impossible.''